SAN FRANCISCO (AP)  A fierce battle is brewing over the future of the Sierra Club, and an unlikely issue is at the center of the debate: immigration.

A growing faction in the nation's most influential environmental group has urged a stronger stance against immigration, calling the growing U.S. population and its consumption of natural resources the biggest threat to the environment.

Past and present Sierra Club leaders say the anti-immigrant faction has teamed up with animal-rights activists in an attempt to hijack the 112-year-old organization and its $100 million annual budget.

"At stake is really the heart and soul of the organization," said Adam Werbach, the club's president from 1996-98. "It's a sad attempt by a very small special-interest group to take over the entire Sierra Club organization."

Some of the old guard has organized a movement called Groundswell Sierra to oppose what they say is an attempted takeover by outside groups. Their opponents responded by filing a lawsuit claiming the leaders are unfairly trying to influence an upcoming board election.

Between March 1 and April 15, members will cast mail-in ballots to fill five open seats on the club's 15-member governing board. The club's anti-immigration faction says it needs only three more seats to control policy.

"It's a democratic process. To accuse these candidates of taking over the Sierra Club is like accusing the Democrats of taking over the White House," said board member Paul Watson, who co-founded Greenpeace and now heads the Sea Shepherd Conservation Society.

Groundswell Sierra was formed after club leaders learned that Watson, who won a seat as a petition candidate last year, spoke openly about a takeover attempt during a speech at a conference on animal rights. Animal rights activists have agitated for the club to denounce hunting, fishing and meat consumption.

Club leaders say the anti-immigration debate has drawn in outsiders who want to promote their agenda. The Southern Poverty Law Center, a Montgomery, Ala.-based civil liberties group, has reported that extremist racist and anti-immigration groups are encouraging their members to pay $25 to join the Sierra Club and vote in the election.

In January, center co-founder Morris Dees said he would run for a board seat to draw attention to the anti-immigration movement.

Groundswell Sierra is encouraging members to vote because less than 10% of the club's 750,000 members have participated in recent elections, making it easy for candidates to win board seats with relatively few votes.

Founded by Scottish immigrant John Muir in 1892, the San Francisco-based Sierra Club, the country's oldest and largest environmental group, has traditionally advocated for clean air and water and protection of wildlands and wildlife.

Despite its swelling ranks — membership has grown by 50% over the past decade — the Sierra Club hasn't had much success at achieving its top priority these days: stopping what members believe is an assault on the environment by the Bush administration, said executive director Carl Pope.

"This administration has played by a different set of rules," Pope said. "If you don't play by the normal rules, you can do a lot of damage — even in three years."

Immigration came to the fore in recent years as some members pointed out that the United States consumes more natural resources than any other country. The debate came to a head in 1998, when members voted by a 60-40 margin to remain neutral on immigration.

But the issue has not gone away. In recent elections, several members who favor tighter curbs on immigration have been elected to the board.

"Many environmentalists are not willing to deal with this very important issue," said board member Ben Zuckerman, a UCLA astronomy professor who co-founded a network of club activists called Support US Population Stabilization. "The numbers need to come down. Legal and illegal immigration are at record-high levels."

Many club leaders say an anti-immigration stance would alienate members as well as allied progressive groups that represent immigrants and minorities.

"The Sierra Club is an inclusive organization," said Groundswell spokesman Lawrence Downing, the club's president from 1986-88. "If the Sierra Club adopted an anti-immigration policy, you've lost your constituency and your credibility."

In an unusual move last month, all 13 living former club presidents sent a letter to the board demanding action to protect the club and endorse the candidates nominated by the board.

Last week, the three most prominent candidates supported by the anti-immigration faction filed a lawsuit against the Sierra Club, seeking to bar the organization from using club resources to back certain candidates.

Board President Larry Fahn called the lawsuit an attempt to "muzzle the leadership."

Watson and his allies, meanwhile, say the group's ruling elite is simply afraid of losing power.

"I think there's a group that's trying to protect their turf," said David Pimentel, a candidate supported by the anit-immigration faction. "They want to run it their way from the inside."

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